Adding Named Objects in Blender with Python API
When you use bpy.ops.object.add() the newly created object becomes the active object, so right after creating the object you can alter it's name with 

bpy.context.active_object.name = 'new_name'


It is also possible to create objects without using operators. This approach will create the objects without altering the existing selection or active object.

import bpy

x = (1.1,2.2,3.3,4.4)
y = (1.1,2.2,3.3,4.4)
z = (1.1,2.2,3.3,4.4)

for index,val in enumerate(x): 
    new_obj = bpy.data.objects.new('new_obj', None) 
    new_obj.location = (x[index],y[index],z[index])
    bpy.context.scene.objects.link(new_obj)


Here 'new_obj' will be the name of the new object, if it is non-unique it will also get a numeric extension.